What is Bitcoin？

創造出比特幣的中本聰Nakamoto Satoshi 在發表論文中的網站中，生日是1975.04.05，也許是個巧合，也可能是記錄著1933年4月5日是美國規定持有黃金是非法的，1975年被改為黃金是合法的日子。

中本聰在發布日就在「創世區塊」中挖礦到50個比特幣，並轉發10個比特幣給予一位好友，是為第一次P2P網路中的交易，而比特幣的總數量只有2100萬或是說是2的50.899次方個；憑空生成比特幣的交易稱為coinbase交易，創始區塊的 coinbase 交易編碼中，有人發現如果把這個16 進制字串變成英數字串再倒過來則是「The Times 03/Jan/2009 Chancellor on brink of second bailout for banks」，是比特幣的創始日與中本聰在最初的交易中留下的訊息，甚為驚奇，比特幣位址是由27到34個之間的英數字所構成的。

Abstract. A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.

在中本聰的論文中沒有出現任何encrypt字眼，只有出現多次的sign，代表著說比特幣並沒有所謂的加密，而是使用者錢包需要有加密的功能，才能用私鑰來保護錢包安全。

文章另會分享在stars blog中，歡迎一起交流。